Offensive lines are one of the most vital parts of a successful football team. When they fail the team tends to fail. They protect the quarterback and open up lanes for the Running back they make the offense actually work. Some exceptions do exist, but for the most part as the line goes so does the team.
Are offensive lines built purely off of talent? No far from. Some of the best O-lines in the league don't have highly sought after athletes. Instead these teams are build on team work and brotherhood.
This is not to say talent doesn't hurt, because it doesn't. If you have talent across the line chances are you O-line will be decent.
So what makes a great O-line? The answer is coaching. The proof is that any team can draft or sign talented lineman yet not every team can have a good O-line. A great coach can turn a unit of sub-par lineman into a top tier unit.
The Atlanta Falcons in 2007 had a horrible O-line and with the addition of only one new starter they became an elite unit. This was because the coach instilled a system that worked for the players which allows them to exceed expectations.
Just remember one thing about O-lines. The O-lines that trust each other and know each other will always out preform the All Star O-lines.